To the Rescue

By J. Bryan Unruh, University of Florida

Spring is now upon us and many gardeners and outdoor enthusiasts are enjoying the warming conditions and sun-filled days that spring ushers in. The old adage “April showers bring May flowers” still holds true, but for many, April showers and May flowers also signal the onset of a busy season battling the Red Imported Fire Ant.

Red Imported Fire Ants (RIFA) (Solenopsis invicta Buren) were accidentally introduced (imported) into the United States at the port of Mobile, Ala., in the 1930s. Originally from South America, the RIFA spread across the southern states in nursery stock and sod during the 1940s and early 1950s. Today, more than 260 million acres in 10 states are infested with this serious pest. Researchers have determined through modeling that the spread of RIFA will likely move north into Oklahoma and Arkansas and are also likely to continue to expand into portions of Virginia, Maryland and Delaware in the east and New Mexico, Arizona, California, Oregon, Nevada and maybe even Washington and Utah in the west.

Left unchecked, fire ant populations can increase very quickly and inflict damage — and even death — on young birds, small animals and livestock, as well as unsuspecting children and adults who are playing or working in their backyards. With a myriad of fire ant control product choices available to lawn care operators, this pest can provide a new business opportunity.

UNDERSTANDING RED IMPORTED FIRE ANTS

In order to understand control strategies, you must understand the biology of these fierce combatants. RIFA live in colonies that contain cream- to white-colored immature ants (eggs, larvae, and pupae), a couple hundred thousand workers, several hundred winged males and winged females (which are unmated queens) and one or more mated queen. The colony generally thrives in an earthen mound, which is essentially an incubator for the brood. In addition to the mound is an interconnected series of underground tunnels, which radiate out from the mound.

Inside the mound, young wingless, sterile female ants work tirelessly tending to the brood — moving it up or down in the mound depending on the external temperature, moisture conditions or invasive predators. Older workers are busy foraging for food (oftentimes at distances of more than 100 feet from the nest) and defending the nest. As we all well know, RIFA are highly aggressive and will attack anything that threatens them. Each worker ant can sting repeatedly by gripping the flesh with its toothed mouthparts and piercing the skin with its stinger mounted on its tail-end.

As spring emerges, winged males and females leave the mound and mate in flight. Shortly after mating, the males will die and the fertilized females become queens who may fly or be blown several miles by wind. After landing and finding a suitable nesting site, the new queen sheds her wings, which makes her vulnerable to predators — especially other ants. If she does survive, she will burrow into the ground and lay a cluster of eggs. After a week or so, the eggs hatch into legless larvae that will go through several growth stages. Larvae will develop for 6 to 12 days, pupate, and then adults emerge 9 to 16 days later. Once a colony is established, a single queen (who mated only once in her life) can lay her weight in eggs daily, producing nearly 2,000 new ants each day of her two- to five-year life span!

CONSUMER EDUCATION IS IMPORTANT

Many homeowners talk about the “home remedies” for controlling fire ants. Although they may appear to work, you need to let your customers know that most home remedies are simply “old wives tales” and have not been proven effective. For example, some say that feeding corn grits to fire ants will cause the ants to swell and explode. This is simply not true. RIFA are omnivorous feeders; they eat everything. However, because of a sieve plate in their throats, they are only able to ingest liquids. When food is found, the worker ants will carry it back to the colony where they place the solid material on a depression in front of the mouth of the oldest larvae that regurgitate digestive enzymes onto the food, breaking it down into liquids. These same larvae then suck up the protein and regurgitate it to the workers, which pass it on to the rest of the colony.

Similarly, some suggest that moving fire ants from one mound to another will encourage the colonies to fight and kill each other. In reality, you will likely get stung if you start handling shovels full of fire ants. Some advocate the use of scalding water to burn the pesky ants. Although this may provide some “control,” typically the mounds have simply relocated and will continue to thrive. Caution should be used since hot water may injure the plants around the mound. And still others promote the use of gasoline and related materials; however, these are not registered for control of fire ants and will more than likely kill the turf and pollute the environment.

MANAGING THE PESKY RED IMPORTED FIRE ANTS

Although routine applications of insecticides for control of grubs, chinch bugs or mole crickets may limit the infestation of RIFA, oftentimes, you may need to implement specific RIFA control strategies. Lawn care operators should consider providing this as an “add-on” service and charge the customer accordingly.

Typically, these specific control strategies involve a two-step approach: baiting and mound treatment. Baits are insecticides incorporated onto a food source that is palatable to fire ants. As fire ants forage for food, they pick up the bait and carry it back to the colony where it becomes part of the food chain. Eventually, the bait will eliminate the reproductive potential of the colony by controlling the queen or disrupting the lifecycle of the ants. Baits may be applied to individual mounds or broadcast over an area depending on the size of the treated area. Most baits are generally applied at very low rates (1 lb. product/acre) and the oily baits can “cake-up” in the application equipment if you are not careful. An added caution with baits is that they tend to go bad soon after the container has been opened and the unused portion is exposed to air. Although purchasing large packages of bait products may be less expensive on a per-pound basis, the unused portions do not last more than a few weeks after the package has been opened.

A second strategy, which is often used in concert with baiting, is to treat individual mounds in sensitive or high-traffic areas with a small amount of quick-acting insecticide, either as drenches, granules or dusts, or injections. As the name implies, drenches are solutions of water and insecticide that you pour onto the mound. For drenches to be effective, the solution must contact all the ants, including the queen. Therefore, drench applications are most effective when made to undisturbed mounds on cool, sunny mornings when the majority of the colony, including the queen and the brood, is situated near the top of the mound where it is warm. Granular or dust formulations of contact insecticides may also be applied to the mound and then, if called for, watered in with 1 to 2 gallons of water. Some insecticides are sold in aerosol cans equipped with a tube that you can insert into the mound and inject the contents into the mound. Just as with drenches and granular insecticides, the insecticide must make contact with the ants to be effective.

Gardeners, outdoor enthusiasts, and families who enjoy the outdoors are intolerant of fire ants. With the new tools available for Red Imported Fire Ant control, you would do well to consider adding this service to your current offerings. However, companies must accurately weigh the strengths and weaknesses of each insect management tool to see how they will best fit into their business strategy to ensure a profitable venture.

J. Bryan Unruh, Ph.D., is associate professor of turf science and Extension turfgrass specialist at the University of Florida IFAS West Florida Research Education Center (Milton, Fla.).